1. Field of the Invention
The present invention relates to a multilayer filter array, which is compact and has capability of considerable noise minimization, and is used in noise elimination for electrical equipment and the like.
2. Description of the Related Art
Demands for miniaturization and weight reduction of equipment whereto electronic components are integrated have been recently increasing; thus, demands for small-sized multilayer electronic components have been rapidly increasing. By integrating a plurality of coils and capacitors respectively, a filter array, which is an arrayed noise filter, has come into use as a type of multilayer electronic component for high-frequency noise countermeasures of circuit boards.
The internal configuration of this conventional filter array, which is an arrayed noise filter, is illustrated in FIG. 9.
In other words, this filter array has a configuration of layered insulator layers 1 through 16, wherein conductive patterns 101A through 109A and conductive patterns 111A through 115A, which respectively configure each signal line of this filter array, are arranged within each respective layer as illustrated in FIG. 9.
In addition, it has a configuration wherein coils 141 through 144 and capacitors 131 through 138 are connected therebetween by input/output terminals 171A through 174B (shown in FIG. 10) of the respective lines, which are provided at both side surfaces of this filter array. Furthermore, it is also a configuration wherein ground terminals 175, 176 (shown in FIG. 10) are arranged at both end surfaces of the filter array.
However, in the configuration of the conventional filter array shown in FIG. 9, the ground conductive pattern 101A, which is shown typified in FIG. 11A, has three narrow portions 121 such as to have a form corresponding to each conductive pattern 102A shown typified in FIG. 11B.
Consequently, inductance has inevitably increased due to making the configuration of each ground conductive patterns 101A, 103A, 105A, 107A and 109A respectively having a plurality of narrow portions 121. In other words, other than coils 160 and 164 actually existing at both end lead-out portions 122 as with the equivalent circuit shown in FIG. 10 of this conventional filter array, coils 161, 162, 163 actually exist so as to correspond to the inner side of these narrow portions 121.
As a result, in consequence of the inductance due to the coil 161, the damping characteristic of the noise filter between the input/output terminals 172A and 172B is degraded. Consequently, there is a drawback of vastly differing characteristics between the damping characteristic of the noise filter positioned between the input/output terminals 171A and 171B (indicated by the dotted line in FIG. 12) and the damping characteristic of this noise filter positioned between the input/output terminals 172A and 172B (indicated by the solid line in FIG. 12), as shown in FIG. 12. Furthermore, it can be similarly said that the damping characteristics of the noise filter between the input/output terminals 172A and 172B and the noise filter between the input/output terminals 173A and 173B differ; and it can be similarly said that the damping characteristics of the noise filter between the input/output terminals 173A and 173B and of the noise filter between the input/output terminals 174A and 174B differ.
On the other hand, a filter array with a distributed-constant construction, whereby signal side coils and ground side coils are opposingly arranged via the insulator layers such that the inductance of each ground side coil mutually correspond, is disclosed in the Japanese Patent Application Laid-open No. 2001-60840. However, with the structure of the filter array disclosed in this publication, since the coil inductance values and the capacitor capacitance values cannot respectively be independently changed, there is the drawback whereby control of damping characteristics is difficult.
The present invention aims to provide a multilayer filter array, which is able to independently adjust inductance and capacitance, as well as make disparity of damping characteristics between signal lines small.
According to a first aspect of the present invention, a multilayer filter array, which is formed by layering a plurality of insulator layers in a state where a plurality of conductive patterns are internally arranged, comprising coils corresponding to respective plurality of lines, which are formed by arranging the plurality of conductive patterns respectively to a single insulator layer; and capacitors corresponding to respective plurality of lines, which are formed by facing the conductive patterns to each other with insulator layers therebetween on insulator layers differing from the insulator layers the coils exist thereupon, wherein only a single conductive pattern, which configures a capacitor corresponding to a respective line, of the capacitors corresponding to respective plurality of lines, is deployed on each respective insulator layer forming each of the capacitors, is provided.
According to such multilayer filter array, operations as in the following take effect.
The multilayer filter array according to this aspect is formed by layering a plurality of insulator layers in a state where a plurality of conductive patterns are internally arranged. Then, coils corresponding to respective plurality of lines are formed by arranging the plurality of conductive patterns respectively to a single insulator layer. In addition, capacitors corresponding to respective plurality of lines are formed by facing the conductive patterns to each other with insulator layers therebetween on insulator layers differing from the insulator layers the coils exist thereupon.
Moreover, it is a configuration wherein only a single conductive pattern, which configures a capacitor corresponding to a respective line, of the capacitors corresponding to respective plurality of lines, is arranged on each respective insulator layer forming each of the capacitors. Thus, the arrangements and configurations of the conductive patterns forming the capacitors are made to differ from those of conventional techniques.
As a result, in this aspect, it has a configuration wherein not only are the coils and capacitors arranged on different insulator layers from each other, but only a single conductive pattern, which configures a capacitor corresponding to a respective line, of the capacitors corresponding to respective plurality of lines, is arranged on each respective insulator layer. Thus, for example, by merely changing the width of the conductive patterns or the number of insulator layers, not only may the inductance of coils be adjusted, but the capacitance of capacitors may be independently and easily adjusted.
Furthermore, signal conductive patterns and ground conductive patterns exist among the conductive patterns forming the capacitors of this aspect. However, by arranging on each insulator layer only a single conductive pattern, which configures a capacitor corresponding to a respective line, of the capacitors corresponding to respective plurality of lines, the narrow portion that existed in the conventional technique multilayer filter array disappears, and the inductance of the ground conductive patterns forming the capacitors becomes small.
Accordingly, since the degradation of the damping characteristics is reduced, the originally designed strong damping characteristics are obtained; moreover since no difference of inductance between each signal line made from the respective ground conductive patterns occurs, difference in damping characteristics between each signal line may be reduced.
Moreover, as the conductive patterns or internal electrodes, which determine the capacity of the capacitors corresponding to respective lines, are not adjacent to each other within the same layer, the capacitor capacity that existed between each line with the conventional techniques does not exist, and cross talk is reduced.
On the other hand, setting the relative dielectric constant of the insulator layers forming the capacitors between 20 and 200, and setting the relative dielectric constant of the insulator layers the coils are arranged thereupon to no more than 15 may be considered as a modified example of the multilayer filter array according to this aspect.
In other words, since the relative dielectric constant of the insulator layers that the coils form is set to no more than 15, the capacitance values between the coils are made smaller, and inter-channel cross talk is reduced. Moreover, taking into account characteristic degradation due to the capacitance generated between the input/output terminals, it is preferable that the relative dielectric constant of the insulator layers forming the capacitors is set to no more than the above-mentioned 200. Furthermore, from the aspect of ensuring the necessary minimum capacitance, it is preferable that the relative dielectric constant of the insulator layers forming the capacitors is to at least the above-mentioned 20.
According to another aspect of the present invention, a multilayer filter array, which is formed by layering a plurality of insulator layers in a state where a plurality of conductive patterns are internally arranged, comprising coils corresponding to respective plurality of lines, which are formed by arranging the plurality of conductive patterns respectively to a single insulator layer; and capacitors corresponding to respective plurality of lines, which are formed by facing the conductive patterns to each other with insulator layers therebetween on insulator layers differing from the insulator layers the coils exist thereupon, wherein only a single conductive pattern, which configures a capacitor corresponding to a respective line, of the capacitors corresponding to respective plurality of lines, is deployed on each respective insulator layer forming each of the capacitors, and external electrodes are arranged on the outside of a main layered body part, which is formed by layering the insulator layers, thereby the coils and the capacitors are connected by these external electrodes, is provided.
According to such multilayer filter array, operations as in the following take effect.
The multilayer filter array according to this aspect has the same configuration as the above-mentioned first aspect; moreover, it has a configuration such that external electrodes are arranged on the outside of a main layered body part, which is formed by layering the insulator layers, thereby the coils and the capacitors are connected therebetween by these external electrodes, which are arranged on the outside of the multilayer filter array. Thus, effective utilization of the internal portions of the multilayer filter array is possible, and in addition, usage of conductive material that passes through via holes and the like of the insulator layers is reduced, allowing for low cost fabrication of the multilayer filter array.
According to yet another aspect of the present invention, a multilayer filter array, which is formed by building up a plurality of insulator layers in a state where a plurality of conductive patterns are internally arranged, comprising coils corresponding to respective plurality of lines, which are formed by arranging the plurality of conductive patterns respectively to a single insulator layer; and capacitors corresponding to respective plurality of lines, which are formed by facing the conductive patterns to each other with insulator layers therebetween on insulator layers differing from the insulator layers the coils exist thereupon, wherein only a single conductive pattern, which configures a capacitor corresponding to a respective line, of the capacitors corresponding to respective plurality of lines, is deployed on each respective insulator layer forming each of the capacitors, and external signal electrodes, which connect to the conductive patterns for signaling, and external ground electrodes, which connect to the conductive patterns for grounding, are arranged side by side on the same side surface of a main layered body part, which is formed by layering insulator layers, is provided.
According to such multilayer filter array, operations as in the following take effect.
The multilayer filter array according to this aspect has the same configuration as the above-mentioned first aspect; moreover, it has a configuration wherein external signal electrodes, which connect to the conductive patterns for signaling, and external ground electrodes, which connect to the conductive patterns for grounding, are arranged side by side on the same side surface of a main layered body part, which is formed by layering insulator layers.
In other words, since the external signal electrodes and the external ground electrodes are arranged in a line on the same side surface of the main layered body part, surfaces of the multilayer filter array with no external electrodes increase. As a result, other electronic devices can be deployed much closer on a printed board whereupon this multilayer filter array is placed, by the virtue of this multilayer filter array. Thus, according to this aspect, higher density layout of electronic devices on printed boards is possible.